Verticillium wilt caused by Verticillium dahliae is a serious vascular disease in cotton (Gossypium spp.). V. dahliae induces the expression of the CAROTENOID CLEAVAGE DIOXYGENASE 7 (GauCCD7) gene involved in strigolactone (SL) biosynthesis in Gossypium australe), suggesting a role for SLs in Verticillium wilt resistance. The research found that the SL analog rac-GR24 enhanced while the SL biosynthesis inhibitor TIS108 decreased cotton resistance to Verticillium wilt. Knock-down of GbCCD7 and GbCCD8b genes in island cotton (Gossypium barbadense) decreased resistance, whereas overexpression of GbCCD8b in upland cotton (Gossypium hirsutum) increased resistance to Verticillium wilt. Additionally, Arabidopsis (Arabidopsis thaliana) SL mutants defective in CCD7 and CCD8 putative orthologs were susceptible, whereas both Arabidopsis GbCCD7- and GbCCD8b-overexpressing plants were more resistant to Verticillium wilt than wild-type (WT) plants. Transcriptome analyses showed that several genes related to the jasmonic acid (JA)- and abscisic acid (ABA)-signaling pathways, such as Myelocytomatosis 2 (GbMYC2) and ABA-insensitive 5, respectively, were up-regulated in the roots of WT cotton plants in responses to rac-GR24 and V. dahliae infection but down-regulated in the roots of both GbCCD7- and GbCCD8b-silenced cotton plants. Furthermore, GbMYC2 suppressed the expression of GbCCD7 and GbCCD8b by binding them to their promoters, which might regulate the homeostasis of SLs in cotton through a negative feedback loop. It was found that GbCCD7- and GbCCD8b-silenced cotton plants were impaired in V. dahliae-induced reactive oxygen species (ROS) accumulation. Taken together, the results suggest that SLs positively regulate cotton resistance to Verticillium wilt through crosstalk with the JA and ABA-signaling pathways and by inducing ROS accumulation.

The research paper was published in Plant Physiol. 2023 Jan 31（IF=8.005）. Ph.D. candidate Feifei Yi is the first author, Prof. Yingfan Cai, Prof. Weiqiang Li and Prof. Lam-Son Phan Tran are the co-corresponding authors.

Paper link: https://doi.org/10.1093/plphys/kiad053